Gyms prepared for heavy traffic by ordering the latest treadmills, scheduling more pilates classes and hiring staff just to process all the membership applications from optimistic resolutioners. While readying the gym for a deluge of newbies is no cakewalk, says Pam Kufahl, editor-in-chief of Club Industry magazine, the real challenge is to get them to stay.

“You may not be able to even handle those people all year, but the more you work to keep them satisfied, the more they’re going to come back and refer you to their friends,” Kufahl says.

Skeptics say gyms take advantage of New Year’s resolutions to rope newbies into year-long contracts, knowing full well they’ll only use two weeks’ worth of them.

“If gyms operate at more than 5 percent of their membership at any given time, no one can use the gym,” branding consultant Peter Shankman says. “They want them to sign up, but they know that after the 15th of January, they won’t see 95 percent of them again.”

New Year’s means big business for overweight-only gym Downsize Fitness, in Chicago and Dallas. Not only does it expect to double, if not triple, membership this month, but Vice President Justin Hazlett says member retention is no sweat. He says the club’s policy of barring membership to anyone shy of 50 pounds overweight makes new members more comfortable.

“Most people who are overweight have a fear of becoming that spectacle in the gym,” Hazlett says. He expanded the Chicago location to triple in size in preparation for the rush and is offering $25,000 worth of prizes to the folks who slim down the most over the next six months.

Most gyms, however, don’t have the same knack for retention. David Reiseman, spokesman for Gold’s Gym, says about half of gym members walk away, perhaps returning to their sedentary lifestyle. “At the end of the day, the toughest part of working out is getting to the gym,” he says.

At least one group is usually happy to see the crowds die down: gym regulars. Vince Morris, 45, uses the StairMaster a couple of times a week at Results Gym in Washington, D.C., but uses less-popular equipment instead every January. He says he’s used to it by now.